In a current wireless communication environment, data request for a network within a wireless communication system has been rapidly increased in accordance with the advent and spread of various devices such as a machine to machine (M2M) device to which M2M communication is applied, a smart phone, which requires high data transmission rate, and a tablet computer. In order to satisfy such increased data request, the communication technology has been developed towards the carrier aggregation technology and the cognitive radio technology, which are intended to use more frequency bands efficiently, and the multi-antenna technology and the multi-base station cooperative technology, which are intended to increase data capacity within a limited frequency. Also, a wireless communication environment has evolved towards a direction that density of nodes that may be accessed by a user is increased. The system having nodes of high density may have higher system throughput through cooperation between the nodes. This system performs cooperative communication by using a plurality of nodes, each of which acts as a base station (for example, advanced BS, Node-B, eNode-B), an access point (AP), an antenna, an antenna group, a radio remote header (RRH), and a radio remote unit (RRU).
Moreover, if all the nodes are transmitted and received under the control of one controller and thus each of the nodes is operated as an antenna group of one base station, this system may be regarded as a single distributed antenna system (DAS). At this time, each node may be given a separate node ID, or may be operated as some antenna within a cell without separate node ID.
In the meantime, if each node performs scheduling and handover with its respective cell ID in the DAS, the system may be regarded as a multi-cell (for example, macro cell/femto cell/pico cell) system. If multiple cells configured by the respective nodes are overlaid in accordance with coverage, it refers to a multi-tier network.
Various types of base stations may be used as nodes regardless of their titles. In other words, a base station (BS), a Node-B (NB), eNode-B (eNB), a pico cell eNB (PeNB), a home eNB (HeNB), RRH, RRU, a relay, and a repeater may be the nodes. At least one antenna is installed in one node. The antenna may mean a physical antenna, or may mean an antenna port, a virtual antenna, or an antenna group. Also, the node may be referred to as a point.
Although the nodes refer to antenna groups spaced apart from one another at certain intervals, they may mean random antenna groups regardless of the spacing. For example, it may be defined that the base station controls a node of H-pol antenna and a node of V-pol antenna.